This invention relates to transdermal, pressure sensitive, adhesive delivery systems for the delivery of an agent, such as a drug, through the skin. More specifically, this invention is directed to such systems which comprise multilayer adhesive matrices.
A well-known method of delivering certain drugs in a controlled manner over time is through the use of a transdermal composition, such as a pressure sensitive adhesive containing the drug. Known delivery systems involve the incorporation of the desired drug into a carrier, such as a polymeric matrix and/or pressure sensitive adhesive formulation. Problems encountered with such delivery systems have included insufficient control over the rate and duration of the transdermal absorption, and a variety of compositions have been developed in efforts to maximize control of the release of a desired drug and the efficacy of the delivery unit.
Although a number of commercially useful transdermal delivery systems have been produced, further improvements are sought.